Electric energy and potential Firdiana Sanjaya 4201414050 Ana

Electric energy and potential Firdiana Sanjaya (4201414050 Ana Alina(4201414095)

Potential Energy � An object near the surface of the Earth has a potential energy because of its gravitational interaction with the Earth � Potential energy comes from an interaction between objects. � There is an electric potential energy associated with interacting charges : � Energy is a scalar, not a vector.

Electric Potential Electric potential is more commonly known as voltage. � The potential at a point a distance r from a charge Q is given by: V = k Q / r � Charges respond to differences in potential in a similar way with pressure to fluid. � Electric potential is a scalar not a vector. � The connection between potential and potential energy is stated as: V = EP / q �

� Equipotential lines are connected lines of the same potential. � If a charge moves along an equipotential line, no work is done; if a charge moves between equipotential lines, work is done.

Potential Difference and Electric Potential � When the test charge is moved in the field by some external agent, the work done by the field on the charge is equal to the negative of the work done by the external agent causing the displacement. This is analogous to the situation of lifting an object with mass in a gravitational field—the work done by the external agent is mgh and the work done by the gravitational force is !mgh.

an infinitesimal displacement ds of a charge, the work done by the electric field on the charge is F. ds = q 0. E. ds � For a finite displacement of the charge from point A to point B, the change in potential energy of the system delta. U =UB - UA is � For

Potential Differences in a Uniform Electric Field When a system consisting of a positive charge and an electric field loses electric potential energy when the charge moves in the direction of the field.

Electric Potential and Potential Energy Due to Point Charges (a) (b) If two point charges are separated by a distance r 12, the potential energy of the pair of charges is given by If charge q 1 is removed, a potential exists at point P due to charge q 2.

Obtaining the Value of the Electric Field from the Electric Potential The electric field E and the electric potential V are related as shown in We now show to calculate the value of the electric field if the electric potential is known in a certain region.

Electric Potential Due to Continuous Charge Distributions The electric potential at the point P due to a continuous charge distribution can be calculated by dividing the charge distribution into elements of charge dq and summing the electric potential contributions over all elements.

Electric Potential Due to a Charged Conductor The surface of any charged conductor in electrostatic equilibrium is an equipotential surface. Furthermore, because the electric field is zero inside the conductor, we conclude that the electric potential is constant everywhere inside the conductor and equal to its value at the surface.

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